\begin{tikzpicture}
    \tkzDefPoints{0/0/B,  2.5/0/C, 3.3/1.5/D, 0.8/1.5/A}
    \tkzInterLL(A,C)(B,D)  \tkzGetPoint{O}
    \tkzDrawPolygon(A,B,C,D)
    \tkzDrawSegments(A,C  B,D)
    \extkzLabelAngel[0.3](B,A,C){$1$}
    \extkzLabelAngel[0.4](D,B,A){$2$}
    \extkzLabelAngel[0.4](B,D,C){$3$}
    \extkzLabelAngel[0.3](D,C,A){$4$}
    \tkzLabelPoints[left](A,B)
    \tkzLabelPoints[right](C,D)
    \tkzLabelPoints[above](O)
\end{tikzpicture}

